Carvin Factory Hot-Rod Mod??

[drano]

Anybody know what this "factory mod" to a Carvin X100-B would have been?

[Reeek]

Although I don't know how it was done (there are schematics available though), I owned one, two actually (1 one w/EL34 and 1 w/6L6, the best one). It was a push pull gain pot that seemed to add another gain stage or two when pull out. Not sure if it was a preamp tube stage added or clipping diodes but it certainly worked. The gain increase was close to double to me ears. I liked it but sold the amp. I had mine tubed with JJ 6L6's and preamp tubes and I biased it with a 110K resistor combo versus the stock 91K so she was running about 41.5 mA, well within the safe range for the plate voltage on that amp. She was really sweet and super creamy. The guy who came over to look at it when I advertised it for sale bought it within 1 minute of playing her.

Just so you know, the bias is set by the ratio of R126 and R127 and changing out R127 is the standard way to alter the bias but a lot of those amps had a trim pot installed after market to facilitate easier biasing. But then, it took me 10 minutes to replace R127 once I got the chassis out and I got lucky and nailed the right value the first time. I had to stack two resisitors to get the 110K value though. I'm not the most patient guy in the world so I worked with what was in my box.

I was basically trying to get away from a head/cab configuration then.

[drano]

Thanks.

One of the things I've heard about the X100-B is that the overdrive is not real gainy - did this mod enhance the distortion a lot did it seem just to be louder?

Is that a no-master silverface Twin in your photos? What year would that be. Never heard of a Sano before. Cool amps there, Reeek.

[Reeek]

Hi, drano,

Yes, the distortion/gain goes way up with that hot rod knob out. No buzziness or graininess at all when biased well. Like Baron55 said in the Amps and Cabs forum, they are way better built and they can sound fantasic with the right bias and tubes. Like I said earlier, smooth and creamy overdrive and no pedals needed. Really.

Yes, that Twin is my baby. It's my uncle's originally bought 1969 Twin with the gray JBL's. I restored it. I still have the JBL logo but it's sort of trashed so I never put it back on after the cabinet was done. My father and uncle were pros then semi pros in "their days". ;) It's been blackfaced by Uncle Spot. He went through all the electonics and changed the bright switch values and some values in the reverb circuit. It runs so quiet that you don't know it's on until you hit the strings . . . JAN Philips 7581A's from KCA and Mullard/RCA preamp tubes :D

The Sano's are TOATALLY AMAZING. The 160R's especially. All three of those run two EL84's and 12AX7 preamp tubes. They were a spin off from Ampeg back in the 50's and lasted until the mid 70's or so.

You have to hear them to believe it. In their own right, they're as good as any tube amp can sound IMHO and I have several benchmark amps. The only issue for some purists (and I consider myself a partial purist) is that they are diode rectified but that is why they sound like 50 watt amps with punch. The 160R's are two of the loudest 16 wattish amps I have ever heard. Both have ceramic 30 watt Blue Dogs in them.